Propeller for steamships.



No. 645,354. Patented Mar. l3, I900.

' C. R. EMRICH.

PROPELLER FOB STEAMSHIPS.

(Application filed June 22, 1899.) (No Model.) 3 SheetsSheat I.

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WITNESSES: lNl/E/VTOR No. 645,354. Patented Mar. l3, l900.-'

' c. R. EMRICH.

PROPELLER FOR STEAMSHIPS.

(Application filed June 22, 1899.)

3 Sheets-Shoat 2.

(No Model.)

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'im i Secwn 072 3- Section on 3 No'. 645,354. Y Patented Mar; l3, I900. C. B. EMBICH. PROPEL LEB FOR STEAMSHIPS.

(Application fllgad June 22, 1899.} (No Model.) 3 Shaets-Sheat 3.

WITNESSES." 1 llVVE/VTOI? ONITEED STATES CHARLES R. EMBIOH, OF NORFOLK, VIRGINIA.

PROPELLER FOR STEAMSHIPS.

SPECIFICATION forming part of Letters Patent No. 645,354, dated March 13, 1900.

Application filed June 22,1899. Serial No. 721,446. (No model.)

To all whom it may concern:

Be it known that I, CHARLES R. EMRICH, a citizen of the United States, residing at Norfolk, in the county of Norfolk and State of Virginia, have invented certain new and useful Improvements in Propellers for Steamships and the Like; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to improvements in the form and construction of propellers for steamships and the like, both as to the shape of the blade in respect of the surface of its driving-face and as to the form and dimensions of the hub in its relation to the blade.

To this end my invention resides in a propeller constructed substantially as hereinafter described. 1

Generally speaking, the blades, which are plural in number, are placed about and project from the hub symmetrically, and all of the blades of one propeller are exactly similar. The driving-face of each blade is made a part of a surface generated by swinging a straight line about the axis of the hub, the said straight line having one end always at a fixed point in the axis of the hub and also in a plane perpendicular to the axis, passing through the position of the generating-line when the latter is perpendicular to the axis, the generating-line to be guided at or near its opposite end by moving along a guide-surface the working edge of which shall be a true helix, having a pitch-angle of forty-five degrees and so set that the axes of the hub and the helix coincide. On the surface so generated the desired outline or perimeter of the blade is laid off. I do not limit myself to any particular outline of each blade, and the pitch-angle of the helix may be varied from forty-five degrees, if desired. The blades should have as little thickness as practicable consistent with necessary strength to resist the breaking effect of the blades action in the Water and to secure a good casting, and this thickness should be added entirely to the backing-face of each blade, which should be as smooth as possible and brought to a keen edge. The construction of the hub will depend upon various considerations, such as whether the blades are to be made integral therewith or detachable; but whatever be the construction of the hub its form should remain substantially the same-that is to say, the surface of the hub between the intersections of the forward and after edges of the blades should be cylindrical in shape, and the exterior diameter of the hub should be no less than that indicated by following formula:

where d represents the diameter of the hub in feet, S represents the working speed of the vessel in knots per hour through the water, It represents the number of revolutions of the propeller at the given'speed of the ship, (p represents the pitch-angle of the guidinghelix, and 7: equals 3.1416. Variations from this diameter may be made to suit the conditions of any particular case of'design, however. The length of the cylindrical part of the hub should preferably be the distance, parallel to the axis, between the intersections ofthe forward and the after edges of the blades with the hubs surface. The hubs surface fore and aft of the intersections of the edges of the blades therewith should be elongated, if necessary, to make attachment to the driving-shaft and taper sufficiently to give fair water leads to the blades. In the case of a solid wheel the hub should be cored out and ribbed for lightness and strength. In the case where detachable blades are to be used the diameter of the hub shall be the same as if solid; but its outer surface shall be made up of the flanges of the blades, the hub proper consisting of a boss carrying a plural num ber of perforated ribs,to which the said flanges of the blades are secured by means of lugs projecting from their cancave faces, as here inafter described.

Referring to the accompanying drawings, wherein I have illustrated the construction of the blades and hub of the propeller, as also the manner of determining the working faces of the former, Figure 1 represents a face elevation of a propeller constructed according to my invention. Fig. 2 represents an edge elevation of the same, the thickness of one blade being indicated in section. Fig. 3 represents an enlarged detail view in face elevation, partly in section, of the hub constructed for detachable blades, three of the blades being partially broken away, one of these shown in section, and a fourth entirely omitted for the sake of illustration. Fig. 4 is a sectional view, the left half of which is taken on the line 3 4 in Fig.3 and the right half of which istaken on the line 3 5 in Fig. 3 looking toward the top of the sheet; and Fig. 5 is a perspective view illustrating the manner of laying off the driving-faces of the blades on a pattern, also illustrating an apparatus for guiding the work of cutting the surface of the driving-face on a pattern, or for sweeping up the surface in loam or sand for a mold.

Referring to Figs. 1 and 2, A represents the blades, the driving-faces a of which, as seen most clearly in Fig. 2, are each generated by swinging a straight line having a fixed point in the axis of the hub, as at w in Fig. 1, from a position at to a position 00 along a guide, the working edge of which, as indicated by the full line y in Fig. 1, is a true helix of a forty-five-degree-pitch angle, corresponding to the right-angle triangle '1" s i, which represents a development of said guide.

Ct, a a and a as shown to the right in Fig. 1, represent the developed contour of the driving-surface of one of the blades.

In Fig. 5 I have shown an apparatus for laying off the driving-faces of the blades. In this figure, 1 represents a vertical standard, rigidly mounted upon a bed-plate 2 and carrying a universal joint 3, the center of which universal joint shall lie in the'aXis of the hub of the propeller and shall be coincident with the fixed point of the generatingline. Aframe 6, preferably arched, as shown, is rigidly connected to the universal joint 3 and carries a straight-edge 7, whose working edge shall correspond with the generatingline, and so carried that its working edge, if extended, would pass through the center of the universal joint, and of such length as to sweep overa su fficiently-large area to include the desired driving-face of one blade.

8 represents the guide set upon the bed-plate at the proper distance from the center of the universal joint, the said guide being of the proper shape and size to give the required surface and to include the driving-face of one blade. This guide here shown may be described as a right-angle forty-five-degree triangle, bent so that one short side (inclicated by the dotted line at 8) coincides with the curvature of a circle whose center is the axis of the blade as determined by the center of the joint 3, the triangle lying in the surface of a cylinder which has such circle as its base and the hypotenuse of the triangle (indicated at 9) representing a true helix, along which the straight-edge 7 is moved in laying off the driving-surface of the blade, as will be readily understood by reference to Fig. 5. This arrangement may be used not only for securing the desired surface. on

a pattern, as indicated at 10 in Fig. 5, but may also be used for sweeping up the surface in loam.

In Figs. 1 and 2 the blades areas are laid off symmetrically about their center lines; but I do not limit myself to this arrangement of the area.

Referring now more particularly to Figs. 3 and 4, which show a construction for detachable blades, B represents a circular boss hav-- ing a central opening 13 for the propellershaft, provided with a groove 71 for a key or feather (not shown) used in securing the boss upon the shaft. The boss B is provided with a plurality of parallel collars B, cut away at regular intervals, as at Z), and perforated, as atvb, for the passage of bolts or keys used in securing the blades, as hereinafter described. These ribs are cut away for the sake of lightness, so that in reality they consist'merely of a plurality ofperforated lugs separated by the said cut-away portions, said parallel collars running transversely to the axis of the propeller-shaft and being divided up by cutaway portions 19 into a plurality of ribs.

0 represents flanges in the form of segments of a circle, upon the outer faces of which are formed the propeller-blades, while upon the inner concave faces of each are formed lugs a, perforated, as at c, to correspond with the perforations in the said ribs, as seen most clearly in Fig. 4. The perforations I) through the said ribs B and the perforations 0 through the said lugs c are preferably tapered in wake of each other for the insertion of taper bolts or keys D, by means of which the blades and hub may be secured firmly-together without any lost motion. From this construction it will be seen that the segmental flanges O, carrying the blades, when fitted together and secured upon the ribs B of the central boss B present a smooth cylindrical surface to the hub. Moreover, the lugs 0, fitting between the collars B, hold the blades against the great strains thereon in line of the axis of the propeller-shaft and give great strength in this direction, which is especially desirable when reversing suddenly;

I do not wish to limit myself to the use of any particular number of ribs or collars, such as B, upon the central boss of the hub, nor to any particular number of lugs upon the segmental flanges O, carrying the blades, as these might be varied as desired to meet the requirements of a particular case.

Having thus described my invention, what I claim, and desire to secure by Letters Patent of the United States, is

1; A propeller for steamships and thelike, having a plurality of blades, the driving-face of each blade being substantially a surface of revolution form ed by a straight line passing through a given point in the axis of the propeller-shaft and guided by a true helix, substantially as described.

2. A propeller for steamships and the like, having a plurality of blades, the driving-face of each blade being substantially a surface of revolution formed by a straight line passing through a given point in the axis of the propeller-shaft and guided by a true helix,whose angle of pitch is forty-five degrees, or approximately forty-five degrees, substantially as described.

3. A propeller for steamships and the like, having a plurality of blades symmetrically disposed about the hub, the driving-face of each blade being substantially a surface of revolution formed by a straight line having one of its ends terminating for all the blades in a common point in the axis of the propellershaft, and its opposite end guided for each blade by a separate helix, all the helices having a common pitch-angle, substantially as described.

4. A propeller for steamships and the like, having a plurality of blades symmetrically disposed about the hub, the driving-face of each blade being substantially a surface of 1 revolution formed by a straight line having one of its ends terminating for all the blades in a common point in the axis of the propellershaft, and its opposite-end guided for each blade by a separate helix, all the helices having a common pitch-angle of approximately forty-five degrees, substantially as described.

5. In a propeller for steamships and the like, the combination with a ribbed hub, of a plurality of bladeshaving flanges meeting together to form a hollow cylinder'inclosing said hub, lugs projecting from said flanges between said ribs, and tapered bolts with nuts thereon securing said ribs and lugs together, substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

O. R. EMRICH.

Witnesses:

G. F. BEACH, J. P. ADAMS. 

